Process of treating hydrocarbons



UNITED STATES PATENT CFFICE.

CHARLES R. DOWNS, OF CLIFFSIIDE, NEW JERSEY, ASSIGNOR TO THE BARRETT COMPANY, A. CORPORATION OF NEW JERSEY.

PROCESS OF TREATING HYDROCARBONS.

No Drawing.

of New Jersey, have invented certain new and useful Improvements in Processes of Treating Hydrocarbons, of which the following is a specification.

This Invention relates to a process of purifying anthracene and separating it from such other products as usually accompany it in tar oils.

One object ofthe invention is to obtain anthracene in a purer'state than the ordinary commercial form, in a rapid, expeditious and economical manner.

Another object is to separate anthracene from other products with which it is often found mixed, thereby facilitating the subsequent separation of one or more such products from each other to obtain the latter in a relatively pure state.

Still another object of the invention is to produce para-anthracene. Other objects and advantages of the invention will be apparent as the description proceeds.

Crude anthracene usually contains mainly anthracene, phenanthrene, carbazol and smaller amounts of diverse compounds all of which may be dissolved in benzol, toluol, or coal tar naphthas, etc., as solvents. Great difliculty has heretofore been experienced in recovering the anthracene from the impurities and its separation in a relatively pure state has necessitated the employment of expensive and laborious processes.

In carrying-out this invention a solution of crude anthracene in benzol, toluol. coal tar naphthas, or other suitable solvent is treated with ultra violet light whereby the anthracene is polymerized and forms para-- anthracene (or di-anthracene) which is very insoluble in the solvent and is accordingly precipitated. At the same time the carbazol, phenanthrene and most of the other compounds ordinarily found mixed with anthracene are unaffected by the ultra violet light and remain in solution. It is customary in this art to refer to polymerized anthracene as para-anthracene or as dianthracene.

The insoluble para-anthracene may be separated by filtration, or other suitable means,

- and may then be reconverted into anthracene by known methods, such as sublimation Specification of Letters Patent.

Application filed July 26, 1918. Serial No. 246,852.

or other suitable means. Commercial anthracene ordinarily contains about 85% to 90% of pure anthracene. As a result of the treatment with ultra violet light, the percentage of pure anthracene in the final procluct has been found to be above 95%. It is to be understood however, that para-anthracene itself is a highly useful product and finds valuable application in the arts without being converted into anthracene and may accordingly be so used, if desired.

In case the crude anthracene contains a large amount of phenanthrene, the phenanthrene may be removed prior to the treatment with ultra violet light, by Washing with a suitable solvent such as benzol or coal tar naphtha in which phenanthrene is more readily soluble than anthracene and carbazol. After the removal of all or most of the phenanthrene the crude anthracene may be dissolved in benzol, etc., and the solution then treated with ultra violet light to obtain substantially pure para-anthracene as a precipitate. At the same time substantially all of the anthracene, which remained undissolved at the end of the phenanthrene washing is separated from theother constituents of crude anthracene in a relatively pure state.

Crude anthracene frequently contains a large percentage of carbazol which remains behind with other impurities after the above mentioned solvent wash and ultra violet light treatment of the crude.

By first removing the anthracene from a crude anthracene containing anthracene and carbazol and no phenanthrene by the ultra violet light, or by removing phenanthrene from a crude anthracene containing anthracene, carbazol and phenanthrene by means of solvent naphtha and then removing anthracene from the residual mixture of anthracene and carbazol by the ultra violet accompanying it as an impurity by means of ultra violet light. This application of ultra violet light is rendered valuable on account of the small mass of the material to be treated and the consequent removal of difficulties in manipulation which often occur when anthracene or anthracene and phenanthrene are present.

In one aspect this invention may be regarded as a new method of purifying anthracene, and in another aspect it may be regarded as a process of removing anthracene from carbazol for the purpose of facilitating the recovery of carbazol from other impurities which are usually found mixed with it. In still another aspect it may be regarded as a method for the recovery ofanthracene. This invention can also be used to produce pure phenanthrene by removing the last traces of anthracene therefrom by means of ultra violet lighzt.

No particular arrangement of apparatus is necessary in practising this invention. 'It

is desirable, however, that the process be carried out in a closed vessel in the absence of air or in the presence of an inert gas, such as nitrogen, in order to prevent oxidation. Oxidation would cause gumming of the mass and interfere with separation and filtration, besides being deleterious in other respects.

Prior process for the recovery 'of anthraw cene and carbazol required the use of pyridin or other expensive solvents, or a caustic potash fusion which is also expensive and unsatisfactory. The prior method of separating pure carbazol from anthracene by means of sulfuric acid is diflicult to carry out and also results in a poor yield of carbazol and aloss of the anthracene present.

In the practice of this process as above described, the use of all expensive reagents is obviated, the yield is high, and the products steps which consist in treating a solution of crude anthracene with ultra violet light, removing the precipitate, and subsequently further purifying the solution.

2. The herein described process which comprises removing phenanthrene from crude anthracene, dissolving the remaining constituents which are soluble in hydrocarsolution of crude anthracene by means of 2 ultra violet light and subsequently separating carbazol from the other impurities.

5. The herein described process which comprises removing phenanthrene bya. suitable solvent and removing means of ultra violet light from crude anthracene and subsequently regaining carbazol from the residue.

6. The herein described process which comprises removing phenanthrene by a suitable solvent and anthracene by means of ultra violet light from crude anthracene and subsequently regaining carbazol from the residue, by means of a suitable solvent.

anthracene by 7. The herein described process which comprises removing phenanthrene by a suitable solvent and anthracene by means of ultra violet light from crude anthracene and treating the residue to obtain relatively. pure carbazol,

8. The herein described process which comprises removing phenanthrene from crude anthracene by means of a solvent, and precipitating anthracene as para-anthracene by means of ultra violet light.

9. The herein described process, which comprises treating a solution of crude an' thracene with ultra violet light while maintaining the solution out of contact with oxidizing agents.

10. The herein described process, which consists in removing phenanthrene from a crude anthracene containing phenanthrene, anthracene, carbazol and other impurities by means of naphtha, extracting anthracene by means of 4 suitable solvent, and treating the residue of partly purified carbazol, while in solution, with ultra violet light to remove the-last traces of anthracene.

11. The herein described process, which comprises removing phenanthrene and anthracene from crude anthracene and treating the residue to obtain relatively pure carbazol.

In testimony whereof I aflix my signature.

CHARLES R. DOWNS. 

